This invention relates to a process for converting solid or liquid organic material to gas having a high heating value.
At the present time, there are available processes for converting solid or liquid organic material to high BTU gas such as methane. However, most of the commercially available processes require a two step procedure which in turn requires high heat input to obtain the desired results. For example, in the wellknown steam-iron process, steam is contacted with iron in a first step to produce hydrogen and to oxidize the iron to FeO. When the reaction is conducted in the presence of organic material, and the appropriate conditions of temperature and pressure are maintained, some hydrogen reacts with carbon to form primarily methane containing minor concentrations of other organic gases. The oxidized iron then is transferred to a second step wherein it is heated under reducing conditions to form iron which subsequently is recycled to the initial iron oxidation step. The process is undesirable since it requires expensive material handling equipment to permit recycling iron and iron oxide between the oxidation and reducing steps. Furthermore, the process has a high heat requirement to effect the endothermic oxidation reaction. Although most of the heat can be recovered from the endothermic reduction step, the heat is low temperature heat which is not useful in providing the temperature requirements of the oxidation step.
It has also been proposed to form high BTU gases such as synthesis gas (H.sub.2 + CO) or methane by the catalytic reaction of superheated steam with low molecular weight hydrocarbons. However, when higher molecular weight hydrocarbons are employed as feeds, excessive undesirable coke formation occurs which deactivates the catalysts employed. By proper choice of catalysts, steam to hydrocarbon ratios, temperatures and pressures, it is presently commercially attractive to employ hydrocarbons having a molecular weight as high as naphtha or desulfurized light petroleum distillates as an organic feed without experiencing excessive coke formation.
It would be highly desirable to provide a process for forming high BTU gas from high molecular weight organic materials, including solids, such as organic waste material or coal to provide good conversions to high BTU gas. Furthermore, it would be desirable to provide such a process which gives little or no conversion to waste solid organic material such as char or coke. In addition, it would be desirable to provide such a process which permits the conversion to high BTU gas relatively quickly so that the need for either large reactors or long residence times in the reactor is not required so that commercially attractive throughput rates can be obtained.